<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <!-- <style>
    button{
      background-color: blueviolet;
      font-style: italic;
      font-size: 25px;
    }
  </style> -->
  <!-- 加载外部样式表 -->
  <link rel="stylesheet" href="./styles/test.css">
</head>
<body>
  <button>外部样式表</button>
</body>
</html>